The automatic transmission apparatus is allocated, for example, to a motor vehicle and preferably lies, in this respect, between a drive apparatus of the motor vehicle and at least one driven axle. The automatic transmission apparatus is used to select, in a driving operation of the motor vehicle, different gear ratios, which are subsequently present between the drive apparatus and the at least one driven axis. The automatic transmission apparatus here provides multiple driving gears, which preferably have gear ratios that are different from one another. For example, several of said driving gears are formed as forward gears and at least one driving gear is formed as a reverse gear.
The automatic transmission apparatus preferably adjusts the gear ratio as a function of an operating state, for example as a function of a torque and/or a rotational speed, particularly of the drive apparatus. The drive apparatus in this case can preferably be designed as an internal combustion engine or, however, as a hybrid drive apparatus, particularly having an internal combustion engine as well as an electric engine.
The automatic transmission apparatus is preferably dealt with by means of a so-called “shift-by-wire” activation. This means that an exclusively electronic and/or optical communication is present between a selector lever and the automatic transmission apparatus, particularly that there is no mechanical and/or hydraulic communication. A driver of the motor vehicle can select the desired gear on the selector lever by shifting the selector lever to a certain setting. For example, the selector lever can be arranged to a park setting “P”, a reverse setting “R”, a neutral setting “N”, and a forward driving setting “D”. The setting of the selector lever is transmitted to the automatic transmission apparatus electronically and/or optically as previously explained, particularly exclusively in this manner.
In order to safely set the motor vehicle in the park setting of the selector lever, that is to prevent the motor vehicle from rolling away, the automatic transmission apparatus provides the parking lock device. Said device has the hydraulic apparatus, which provides the hydraulic cylinder and the hydraulic piston. The hydraulic piston is arranged so that it can be shifted in the hydraulic cylinder. The lock apparatus, by means of which the hydraulic piston can be set in one of at least two positions within the hydraulic cylinder, is allocated to the hydraulic cylinder or the hydraulic piston.
The pressure present in the hydraulic cylinder can be adjusted using the hydraulic valve. The position of the hydraulic piston within the hydraulic cylinder depends here—provided it is not set by means of the lock apparatus—on this pressure. In this respect, the position of the hydraulic piston within the hydraulic cylinder can be adjusted by way of the hydraulic valve; in particular, it can be adjusted in a controlled and/or regulated manner. Preferably, the shifting shaft can be shifted exclusively within the operating position range by means of the hydraulic apparatus.
With the assistance of the hydraulic valve, the hydraulic piston can be shifted in this respect only into positions that correspond to positions of the shifting shaft in the operating position range. The shifting shaft, which is allocated to the park locking device, is operatively connected to the hydraulic piston. The park locking device is either activated or deactivated, as a function of its setting or the setting of the hydraulic piston in the hydraulic cylinder, by means of the shifting shaft. Within the operating position range, there is a first position with respect to this, in which the shifting shaft is arranged in such a way that the park locking device is deactivated, while a second position is present as well within the operating position range, in which the park locking device is activated.
When the park locking device is activated, the automatic transmission apparatus is blocked, so that a torque transfer from an input shaft of the automatic transmission apparatus to an output shaft and/or the reverse is suppressed. Preferably, at least the output shaft is blocked when the park locking device is activated. The input shaft is preferably operatively connected or can be operatively connected to the drive apparatus, while the output shaft is operatively connected or can be operatively connected to the at least one driven axle of the motor vehicle.
For example, the lock apparatus is then used to set the hydraulic piston and/or the shifting shaft either in the first position or the second position. When the lock apparatus is activated, the hydraulic piston and the switching shaft are set, in this respect, in such a way that they cannot be moved out of the instantaneously present position, particularly not out of the first position and/or the second position. With the assistance of the lock apparatus, thus the instantaneous operating state of the park locking device is reliably maintained, so that it cannot result in an unintentional rolling movement of the motor vehicle and/or an unintentional blocking of the automatic transmission apparatus while the motor vehicle is traveling.
Should this result in a malfunction in the automatic transmission apparatus, particularly in the park locking device, it is possible for the motor vehicle to essentially be ready for travel but that the park locking device will not allow a driving operation of the motor vehicle. For this reason, the driver of the motor vehicle is given the option of deactivating the park locking device by means of the emergency unlock apparatus. The emergency unlock apparatus enables, for example, a manual shifting of the shifting shaft. However, with known automatic transmission apparatuses, it cannot be determined whether the park locking device was deactivated by means of the emergency unlock apparatus.